In industrial plants, particularly thermo-mechanical machines and chemical plants, in which different fluids are used, it may be necessary to keep those fluids separate from one another within the plants. For example, in thermal combustion power plants, flow regions of hot combustion gases have to be separated sealingly from flow regions of cooling gases of lower temperature. In gas turbine plants with high turbine inlet temperatures, for example of more than 1000° C., thermal expansions of the individual components of the gas turbine plant occur, so that adjacent components are sometimes spaced from one another through the use of a gap in order to avoid high thermal stresses and the formation of cracks. Such gaps may constitute connections between flow regions of hot gases and flow regions of cold gases. It is advantageous to seal off the gap to reduce the inflow of cold gas into the flow region of hot gases so as not to thereby lower the temperature in the flow region of hot gases.
U.S. Pat. No. 3,341,172 and U.S. Pat. No. 2,991,045, each of which describes a gas turbine with an outer casing and a two-part inner casing, accordingly specify a sealing element that has a cross-section in the shape of an elongate C for sealing a gap between the two inner casings. An annular gap, through which cooling fluid is guided, is formed between the inner casing and the outer casing. The hot gas for driving the gas turbine flows within the inner casing.
U.S. Pat. No. 4,537,024 describes a gas turbine plant, in which components of a nozzle structure are sealed through the use of axial and radial sealing elements. The sealing elements are intended to prevent hot gas which flows through the nozzle structure from infiltrating into turbine regions outside the hot-gas duct. A sealing element can have approximately the shape of a squashed eight as seen in cross-section.
U.S. Pat. No. 5,975,844 describes in an assembly including two mutually thermally movable components each having a component groove located one opposite the other, a sealing element. This sealing element is directed along a main line for sealing a gap between the components. It comprises a first end, a second end opposite the first end and a middle region, in a cross-section substantially perpendicular to the main line, along a centre line, whereby the middle region is disposed between the ends and the sealing element having a toothed first surface.
U.S. Pat. No. 5,657,998 relates to a gas-path leakage seal for generally sealing a gas-path leakage-gap between spaced-apart first and second members of a gas turbine, in particular first and second segments of a gas turbine combustor casing. This seal comprises a generally imperforate foil-layer assemblage consisting essentially of materials selected from the group consisting of metals, ceramics, and polymers. This foil-layer is impervious to gas and it is disposed in the gas-part leakage-gap. The foil-layer assemblage having a first foil-layer with a lengthwise direction. The gas leakage seal further comprises a cloth-layer assemblage covering and contacting generally the entire first foil-assemblage outer surface and consisting essential of materials selected from the group consisting of metals, ceramics and polymers. Preferably the cloth-layer assemblage has two layers each have a thickness of about 10–25 microns. The cloth-layers each are woven cloth-layers and each comprises a high temperature, nickel-based super-alloy, such as Inconel X-750. The seal assemblage is either fixed in grooves of adjacent parts of a gas turbine, or introduced in a U-shape flange of a combustor, or used in a twin-seal installation or in a multi-seal installation. In either case the seal fully lies within the leakage-gap, and provides a sealing effect either by contacting a surface within the gap, being inserted in a groove or contacts another seal assemblage. In comparison to a conventional metal rigid seal this seal with two foil-assemblages reduces the gas-path leakage from 2.4% to generally 1.0% according to U.S. Pat. No. 5,657,998.